Regeneron's Fianlimab-Libtayo Combo Falls Short Against Merck's Keytruda

Regeneron Pharmaceuticals' (REGN) experimental drug combination of fianlimab and Libtayo has failed to prove superior to Merck's Keytruda in a pivotal late-stage melanoma trial. The company announced that while the fianlimab arm showed a numerical improvement in progression-free survival, this difference was not statistically significant.

The trial tested the combination against Keytruda in patients with advanced melanoma and found that those on the high-dose of fianlimab plus Libtayo lived a median of 11.5 months without their cancer worsening, compared to 6.4 months for those on Keytruda alone. However, this difference was not statistically significant.

Regeneron shares slipped marginally in after-hours trading following the announcement and the company's setback is seen as a disappointment in its efforts to carve out a position in the fast-growing melanoma immunotherapy market. The company continues to test the same combination against Bristol Myers Squibb's Opdualag in a separate late-stage trial.